This invention relates to a building having a floor-by-floor electromagnetic shield structure well-suited for application to an information network system in which an electromagnetically shielded space is divided by individual floors and electromagnetic waves are utilized within the building on a floor-by-floor basis.
In many modern buildings, information generally is communicated between the interior and the outside of the building by making joint use of information communicating equipment such as multiple electronic exchanges and computers. With the increasing value of information, diversification of user needs and increasingly individual nature thereof, the amount of information involved in such communication is growing. Under these circumstances, how to supply the necessary information rapidly and at low cost has become of prime importance. In an effort to satisfy this need, data highway-type information networks utilizing optical fiber cables or coaxial cables have been studied and proposed.
However, with a data highway system utilizing optical fiber cables or coaxial cables, the cables must be stretched throughout all parts of the building to reach the various terminals. Laying these cables requires additional time and expenses.
If electromagnetic waves are used to transmit information, laying cables is unnecessary. However, owing to the emission of electromagnetic noise waves from such a building, certain restrictions apply when electromagnetic waves are used. Another problem is that the communication system may malfunction due to electromagnetic waves from outside the building.
Accordingly, the applicant has separately proposed a building within which communication by electromagnetic waves is made possible by using electromagnetic shielding materials in the body of the building and in such building openings as windows and doorways so that the entire outer periphery of the building has an electromagnetic shield structure. However, when information is communicated by electromagnetic waves in a building of this kind and an n-channel frequency band is allotted for each floor, a frequency band of n.times.m channels is necessary if the building has m floors. This means that if the frequency band width of each channel is, say, 25 kHz, then the frequency band width necessary for a case where the entire interior of the building is to be designed as a single electromagnetically shielded space will be 25 kHz.times.n.times.m. Consequently, the required frequency band width (the required number of channels) increases as the number of floors and the amount of traffic increase. Problems that result are an increase in the size and scale of the communications equipment and higher costs.